Need Help - PlayBook Restarted!

Dear PB Users,
Need your help with understanding what just happened with my playbook. I was reading articles here using Simple Browser and found about an app so did a google search on it in a new tab, opened the app provider's website in the 3rd tab and, finally, followed the download link from the website that opened in the 4th tab.
I was reading reviews on the app world tab and then pb stopped responding to my touch. After about 25 seconds, it restarted on its own and now I'm telling you all about it writing on my pb.

The point that I really want to make is that, although, I opened all 4 tabs that is the maximum i could using the Simple Browser, i didn't get any low memory warning or anything of that sort. Yes, i didn't turn off the pb for last 2 days. Do you think that pb needs a reboot every day like our bb phones (when used heavily)?

Please include what I can do to avoid the situation like this in future.
Thanks in advance for your help.

P.S. I didn't have any other app running except the Simple Browser. Have been using Simple Browser for quite some time but never had this kinda problem. Yes, all my background tabs were active and i run my pb in the "showcase" mode.

Hard reboot and go from there. Hold volume + - & power button down at the same time for about 10 seconds or until it turns off & reboots.

It restarted and running fine since then. I wonder why I should hard reboot it. Do you think that it can happen again if not performed a hard reboot? Please guide me in the right direction. Thanks for your last comment/ help.

Maybe showcase mode had something to do with it. That might have put too much of a load on the PB multitasking. This mode probably also chews battery but maybe you run it plugged in.

I'll try turning off "showcase" mode for 2-3 days and will report back any difference noticed. As far as battery backup, i get about 9 hours on tethering but I've to put my phone on charge after about 6 hours.